Tolerance display system

ABSTRACT

A tolerance display system allows workers to easily obtain accurate size information at actual worksites. The tolerance display system includes a tolerance display device which has a storage device storing standards data/files related to general tolerance, an information input device for inputting information, an operation unit for reading out standards data related to a general tolerance from the storage device based on data input by the information input device and calculating limits of size, and an output device for displaying the standards data, the limits of size and other information. The information input device includes an industry type menu input portion for selecting and inputting a product name of a desired industry type, a specified condition input portion for inputting specified conditions such as a special item, a tolerance class, a basic dimension, and a numerical value/arithmetic operator input portion for inputting a numerical value/arithmetic operator.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tolerance display system, and moreparticularly, to a tolerance display system used by workers engaged inworking on various products such as iron castings, open die forgings,aluminum alloy castings, steel castings, metallic sintered products, diecastings, parts formed by shear working of sheet metal, and parts formedby press working of sheet metal. The display system displays generaltolerance information without direct individual tolerance indication inmanufacturing drawings, and limits of size calculated based on suchdrawings.

2. Description of the Related Art

In manufacturing drawings used in worksites in various manufacturing andmachining industries, dimensional tolerances, for example, based onnational standards are indicated. The general dimensional tolerance(permissible deviation in dimensions without tolerance indication) meantfor simplifying indications in drawings have no individual toleranceindication and no tolerance indication for individual sizes on drawings,but are given collectively in the form of a list of standards. Thegeneral tolerance is mainly applied to the dimensions of parts that donot require particularly high precision in view of their functions.

In working at actual worksites, the general tolerance is still veryimportant and indispensable information in manufacturing high qualityproducts, but such information is not included in the dimensions givenin drawings.

Meanwhile, conventionally, in worksites in various manufacturing andmachining industries, general tolerances are known to workers only basedon their sense and experience of many years or through a list ofstandards. In some cases, general tolerance values available from thestandards list are used to calculate limits of size on paper or using adesktop calculator (hereinafter simply as a “calculator”), and theresults are added or used for correction of the sizes given on themanufacture drawings.

According to the conventional method, however, the operation heavilydepends on the experience and sense of workers, in other words on theirmemory. As a result, accurate limits of size are sometimes not availablewhen the workers are in error. It is difficult and time consuming toreview the standards list, carry out calculation on paper or using acalculator based on the obtained values of general tolerances, and thenfinally add or correct dimensions on the actual manufacture drawings. Itis highly possible that workers may read incorrect values of generaltolerances by mistake when they review the list. The standards lists areoften kept at offices that are remote from worksites, or in reality theycannot easily be carried, in other words, they are not easy to use forthe workers.

Therefore, in the conventional methods, accurate dimensional informationnecessary for producing high quality products, in other words, limits ofsize, are not readily and easily available to the workers.

SUMMARY OF THE INVENTION

In order to overcome the problems described above, preferred embodimentsof the present invention provide a tolerance display system that allowsaccurate dimensional information to be easily available to workers atactual worksites.

A tolerance display system according to a preferred embodiment of thepresent invention includes a storage device storing standards data andfiles related to a general tolerance, an information input device forinputting prescribed information, an operation unit for reading outstandards data related to the general tolerance from the storage devicebased on data input by the information input device, and calculatinglimits of size, an output device for displaying the input data, thestandards data, and the limits of size, and a controller formanaging/controlling the storage device, the input device, the operationunit and the output device. The information input device includes anindustry type menu input portion for selecting and inputting an industrytype represented by the type of a desired product, a specified conditioninput portion for inputting a specified condition such as a specialitem, a tolerance class, and a basic dimension, and a numericalvalue/arithmetic operator input portion for inputting a numericalvalue/arithmetic operator.

In the tolerance display system, the industry type menu input portionmay include an industry type menu input keyboard for selecting anindustry type, for example, represented by the name of a desiredproduct, the numerical value/arithmetic operator input portion mayinclude a numerical value/arithmetic operator input keyboard forinputting a numerical value/arithmetic operator, and the specifiedcondition input portion may include a special item input keyboard forinputting a special item such as the type of shape, the type of product,the type of a manufacturing method, the type of material, the type ofsize, and the type of a geometrical characteristic, a basic dimensiondivision input keyboard for selecting the division of a basic dimension,a tolerance class input keyboard for selecting a tolerance class and ageneral tolerance input keyboard for inputting a calculated generaldimensional tolerance.

In the tolerance display system, the standards data may automatically beretrieved based on each input data, and a calculation processing forlimits of size related to the special item of the input industry typemenu may be carried out.

In the tolerance display system, it is more effective that the inputdata, the retrieved standards data, the limits of size obtained by thecalculation processing and the unit thereof are displayed by the outputdevice.

In the tolerance display system according to preferred embodiments ofthe present invention, using the industry type menu input portion, anindustry type, for example, represented by the type of a desired productis selected, and any of standards data/files stored in the storagedevice in advance is accessed in order to specify the range ofapplication for specifying general dimensional tolerances for thedesired product. Then, using the information input device, prescribedspecified conditions are input, and desired standards data related tothe specified conditions are automatically retrieved. Then, using theoperation unit, retrieval/calculation result information such as generaltolerances and limits of size based on the general tolerances isobtained. The retrieval/calculation result information thus obtained isdisplayed by the output device.

The foregoing and other elements, characteristics, features, andadvantages of the present invention will become more apparent from thefollowing detailed description of preferred embodiments of the presentinvention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a preferred embodiment of the presentinvention;

FIG. 2 is a system flowchart for use in illustration of the preferredembodiment shown in FIG. 1;

FIG. 3 is a system flowchart for use in illustration of the preferredembodiment shown in FIG. 1, continued from FIG. 2;

FIG. 4 is a system flowchart for use in illustration of the preferredembodiment shown in FIG. 1, continued from FIG. 3;

FIG. 5 is a system flowchart for use in illustration of the preferredembodiment shown in FIG. 1, continued from FIG. 4;

FIG. 6 is a system flowchart for use in illustration of the preferredembodiment shown in FIG. 1, continued from FIG. 5; and

FIG. 7 is a system flowchart for use in illustration of the preferredembodiment shown in FIG. 1, continued from FIG. 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a diagram showing a preferred embodiment of the presentinvention.

A tolerance display system according to the present preferred embodimentincludes a tolerance display device 10. The tolerance display device 10has a digital calculator function like a desktop calculator capable ofcarrying out the four arithmetic operations and is in an easy to carry,compact, twofold (double spread) form, for example. Therefore, thetolerance display device 10 can easily be carried by a worker in anactual worksite and provide high operability.

The tolerance display device 10 includes a storage device storingstandards data/files related to general tolerances according to nationalstandards such as Japanese Industrial Standards (JIS). The storagedevice preferably includes a ROM file, for example. The ROM filepre-stores various standards data including special items in connectionwith the general tolerance. The data includes lists of divisions ofbasic dimensions, tolerance classes, general dimensional tolerances andthe like specified by JIS, product names, working methods, theapplicability of materials for each individual industry type to whichthe standards data is applied, general items, terminology, instructionson drawings, notes, and the like.

Note that RAM files may be used instead of ROM files. The tolerancedisplay device 10 according to the preferred embodiment has a minimumcalculation function to carry out four arithmetic operations for twelvedigit numbers, for example. The device 10 includes a storage devicehaving a minimum storage capacity about in the range from 512 KB to 1024KB, for example.

The tolerance display device 10 includes an information input device forinputting various types of standards data related to the generaltolerances and prescribed specified information in association with thedata, so that the data can be effectively utilized.

For example, the information input device includes an industry type menuinput keyboard 12 as a first input portion (industry type menu inputportion) for selecting and inputting an industry type menu representedby a product name for a desired industry type. The industry type menuinput keyboard 12 is provided on the upper right side of the tolerancedisplay device 10.

There is a specified condition input keyboard group 14 as a second inputportion (specified condition input portion) provided near the industrytype menu input keyboard 12 for inputting specified conditions such as aproduct name, a special item, a basic dimension, and a tolerance class.The specified condition input keyboard group 14 includes a special iteminput keyboard 16 used to input a special item such as a working methodand a material, a basic dimension input keyboard 18 used to input thedivision of a basic dimension, and a tolerance class input keyboard 20used to input a tolerance class. There is a numerical value/arithmeticoperator input keyboard 22 as a third input portion (numericalvalue/arithmetic operator input portion) used to input individualnumerical values, or carry out an arithmetic operation on the left sideof the tolerance display device 10.

Note that these various input keyboards are formed and arranged so thatcharacters, symbols, drawings and the like are visually simple andcalculation can be carried out by simple operation.

The tolerance display device 10 has an operation unit that reads outstandards data related to a general tolerance from the storage devicebased on data input by the information input device, and calculateslimits of size for a working method for a desired product using a storedlimits of size calculation program/file or the like. An upper portion ofthe numerical value/arithmetic operator input keyboard 22 is aninput/output display screen 24. The screen defines an output device fordisplaying various types of input/output data such as input data,standards data related to general tolerance and limits of size. Notethat the input/output display screen 24 according to the presentpreferred embodiment is preferably a liquid crystal display screenhaving a display function for about 128×64 dots, for example.

The tolerance display device 10 has a controller formanaging/controlling so that the storage device, the information inputdevice, the operation unit and the output device operate in a regulatedmanner and appropriately in cooperation with each other. According tothe present preferred embodiment, the operation unit and the controldevice are implemented by a single central processing unit (CPU).

In the tolerance display device 10, an industry type menu desired to beactivated is selected using the industry type menu input keyboard 12 andthen standards data/files related to pre-stored general tolerance areaccessed. Then, using the specified condition input keyboard group 14,prescribed specified conditions are input. Then, specified products,working methods, material names, divisions of basic dimensions,tolerance classes and the like are automatically retrieved from thedatabase related to the input specified conditions and displayed on theinput/output display screen 24 as retrieval result information. Theretrieval result on the input/output display screen 24 is checked asrequired, and this operation is repeated a number of times, so thatdesired limits of size (allowable maximum size and allowable minimumsize) are finally available to the user (worker).

With reference to the flowcharts in FIGS. 2, 3, 4, and 5, a system forcalculating general dimensional tolerance, for example, for parts formedby press working of sheet metal and limits of size based thereon will bedescribed as an example of a tolerance display system using thetolerance display device 10 according to the present preferredembodiment.

The power supply key (AC) of the numerical value/arithmetic operatorinput keyboard 22 is turned on. Keys at the industry type menu inputkeyboard 12 are pressed to command program activation and activates thelimits of size calculation program/file. According to the proceduredisplayed on the input/output display screen 24, various types of dataare input such as an industry type (product name)=parts formed by pressworking of sheet metal, a special item (kind of press working) punching,a basic dimension=50 mm, and tolerance class=A. Then, the worker isrequested to check whether the content of the input conditionspecifications is correct on the input/output display screen 24.

When the content of the input condition specifications is confirmed tobe correct, an input condition specification confirmation key 26 ispressed once to enter OK. In this case, the “OK” is indicated on theinput/output display screen 24 in response to the single pressing of theinput condition specification confirmation key 26. When the key ispressed twice, “NO” is indicated. In that case, the execution key 28 maybe pressed after the displayed content is confirmed. Then, acorresponding general dimensional tolerance of ±0.15 (unit: mm) isretrieved from standards data/files related to the general dimensionaltolerance, and displayed together with the basic dimension on theinput/output display screen 24. According to the procedure displayed onthe input/output display screen 24, the thus retrieved generaldimensional tolerance, ±0.15 is input using the numericalvalue/arithmetic operator input keyboard 22 and the execution key 28 ispressed. Then, calculated data for the range of actual working sizes(allowable maximum and minimum size (unit: mm)) is displayed on theinput/output display screen 24.

After acknowledging the desired limits of size, the worker selectswhether or not to continue the operation. When the operation is to end,the operation end key 30 is pressed to end the operation. The operatorthen starts manufacturing the product based on the calculated actualworking sizes (allowable maximum and minimum size (unit: mm)). If theoperation is to be continued, the control returns to the initialoperation and keys on the industry type menu input keyboard 12 are onceagain pressed to activate the activation program, and the above flow maybe repeated according to the procedure displayed on the input/outputdisplay screen 24.

The conventional systems depend on the worker's expertise or sense orthe worker's efforts to find general dimensional tolerance by referringto JIS standards lists, and add or correct sizes displayed on actualmanufacture drawings. In this way, necessary working sizes, in otherwords, limits of size are obtained. Meanwhile, by the tolerance displaysystem according to the present preferred embodiment of the presentinvention, the following effects are provided.

More specifically, the effects of the tolerance display system accordingto the preferred embodiment are:

-   -   (1) Data such as product names, working methods, material kinds,        tolerance classes, symbols, descriptions, divisions of basic        dimensions, general dimensional tolerances, remarks, and notes        are arranged and stored in databases, and therefore necessary        working size information is available without much effort simply        by operating the information input device. As a result, the time        required for checking can significantly be shorter than the        conventional methods.    -   (2) Since the JIS standards data relating to general tolerance        is provided in the form of databases, errors such as reading        wrong values which are likely to happen in the course of        manually checking the actual JIS standards lists can be        prevented.    -   (3) Since the program used to calculate limits of size        (allowable maximum and minimum size) based on general tolerance        is stored, calculation can be carried out by inputting necessary        information using the information input means. As a result,        calculation mistakes can significantly be less than the case of        calculating individual values.

Note that in the described preferred embodiment, the tolerance displaysystem using Japanese Industrial Standards (JIS) is used as an exampleof standards related to tolerance. Meanwhile, the present invention isnot limited to this, and standards data related to tolerance used in acountry of interest can be used among various other countries to whichthe tolerance display system is applied.

More specifically, in the tolerance display system according topreferred embodiments of the present invention, standards data/filesthat can be stored in the storage device include those related tovarious tolerances, for example by American National Standards Institute(ANSI), Chinese Industrial Standards (CIS), Korean National Standards(KS), German Institute for Standardization (DIN), British StandardsInstitution (BSI), Italian National Agency of Unification (UnificazioneItaliano, UNI), European Standards (EN), and International Organizationfor Standardization (ISO).

As described above, according to preferred embodiments of the presentinvention, the tolerance display system that allows workers to easilyobtain accurate size information in actual worksites is provided.Therefore, the tolerance display system according to the preferredembodiments eliminates errors caused by careless mistakes by theworkers, and therefore the workers can feel at ease during working.Therefore, losses by defects can significantly be reduced, andconsiderably high quality products can be manufactured.

While preferred embodiments of the invention have been described above,it is to be understood that variations and modifications will beapparent to those skilled in the art without departing the scope andspirit of the invention. The scope of the invention, therefore, is to bedetermined solely by the following claims.

1. A tolerance display system, comprising: a storage device storingstandards data/files related to a general tolerance; an informationinput device arranged to input prescribed information; an operation unitarranged to read out standards data related to said general tolerancefrom said storage device based on data input by said information inputdevice, and calculating limits of size; an output device arranged todisplay said input data, said standards data, and said limits of size;and a controller arranged to manage and control said storage device,said input device, said operation unit and said output device; saidinformation input device including: an industry type menu input portionfor selecting and inputting an industry type represented by the type ofa desired product; a specified condition input portion for inputting aspecified condition including at least one of a special item, atolerance class, or a basic dimension; and a numerical value/arithmeticoperator input portion for inputting a numerical value/an arithmeticoperator; wherein said industry type menu input portion includes anindustry type menu input keyboard for selecting an industry typerepresented by a name of a desired product, said numericalvalue/arithmetic operator input portion includes a numericalvalue/arithmetic operator input keyboard for inputting a numericalvalue/an arithmetic operator, and said specified condition input portionincludes a special item input keyboard for inputting said special itemof interest including at least one of the type of a shape, the type of aproduct, the type of a working method, the type of a material, the typeof a size, the type of a geometrical characteristic, a basic dimensiondivision input keyboard for selecting the division of said basicdimension, a tolerance class input keyboard for selecting said toleranceclass or a general tolerance input keyboard for inputting a calculatedgeneral dimensional tolerance.
 2. The tolerance display system accordingto claim 1, wherein said standards data is automatically retrieved basedon said input data, and a calculation processing for limits of sizerelated to the special item of said input industry type menu is carriedout.
 3. The tolerance display system according to claim 1, wherein saidinput data, said retrieved standards data, said limits of size obtainedby the calculation processing and the unit thereof are displayed by saidoutput device.
 4. A tolerance display system, comprising: storage meansstoring standards data and files related to a general tolerance;information input means for inputting prescribed information; operationmeans for reading out standards data related to said general tolerancefrom said storage means based on data input by said information inputmeans, and calculating limits of size; output means for displaying saidinput data, said standards data, and said limits of size; and controlmeans for managing and controlling said storage means, said input means,said operation means and said output means; said information input meansincluding: an industry type menu input portion for selecting andinputting an industry type represented by the type of a desired product;a specified condition input portion for inputting a specified conditionsuch as a special item, a tolerance class, or a basic dimension; and anumerical value/arithmetic operator input portion for inputting anumerical value/an arithmetic operator; wherein said industry type menuinput portion includes an industry type menu input keyboard forselecting an industry type represented by a name of a desired product,said numerical value/arithmetic operator input portion includes anumerical value/arithmetic operator input keyboard for inputting anumerical value and an arithmetic operator, and said specified conditioninput portion includes a special item input keyboard for inputting saidspecial item of interest including at least one of the type of a shape,the type of a product, the type of a working method, the type of amaterial, the type of a size, the type of a geometrical characteristic,a basic dimension division input keyboard for selecting the division ofsaid basic dimension, a tolerance class input keyboard for selectingsaid tolerance class armor a general tolerance input keyboard forinputting a calculated general dimensional tolerance.
 5. The tolerancedisplay system according to claim 4, wherein said standards data isautomatically retrieved based on said input data, and a calculationprocessing for limits of size related to the special item of said inputindustry type menu is carried out.
 6. The tolerance display systemaccording to claim 4, wherein said input data, said retrieved standardsdata, said limits of size obtained by the calculation processing and theunit thereof are displayed by said output means.